Systems and methods for testing and calibrating a focused ultrasound transducer array

Abstract

Systems and methods for testing the performance of a focused ultrasound transducer array include transmitting ultrasonic energy from the transducer array towards an acoustic reflector, such as a planar air mirror, and receiving ultrasonic energy reflected off of the acoustic reflector using a sensing element. A characteristic of the reflected ultrasonic energy, such as amplitude and phase, is measured by processing circuitry, for example, by comparing the characteristic of the received ultrasonic energy to a corresponding characteristic of the transmitted ultrasonic energy to obtain an actual gain and phase shift for the received ultrasonic energy. A controller compares the actual gain and phase shift of the received ultrasonic energy to an expected gain and phase shift of the received ultrasonic energy. This information is used to calibrate the transducer array and/or to declare a system failure if the comparison indicates an error.

What is claimed is:  
     
       1. A method for testing a focused ultrasound transducer, comprising: 
       locating an acoustic reflector in a position to receive an ultrasonic signal transmitted by the transducer;  
       transmitting an emitted ultrasonic signal from the transducer towards the acoustic reflector;  
       receiving a reflected ultrasonic signal reflected off of the acoustic reflector;  
       evaluating the transducer performance based upon the received reflected ultrasonic signal; and  
       using an estimation algorithm to estimate any deviation in alignment between the acoustic reflector and transducer;  
       wherein the step of evaluating the transducer performance comprises adjusting the transducer performance evaluation based upon the estimated deviation to correct for any misalignment between the acoustic reflector and the transducer.  
     
     
       2. The method of  claim 1 , wherein the estimation algorithm comprises performing a least squares fit on measured phase deviations from a plurality of transducer elements comprising the transducer to yield an approximation of any deviation in alignment between the acoustic reflector and the transducer. 
     
     
       3. A method for testing a focused ultrasound transducer, comprising: 
       locating an acoustic reflector in a position to receive an ultrasonic signal transmitted by the transducer;  
       transmitting an emitted ultrasonic signal from the transducer towards the acoustic reflector;  
       receiving a reflected ultrasonic signal reflected off of the acoustic reflector; and  
       evaluating the transducer performance based upon the received reflected ultrasonic signal;  
       wherein the transducer has a geometric focal point, and wherein the acoustic reflector comprises a planar reflector located half-way between the transducer and the geometric focal point.  
     
     
       4. The method of  claim 3 , wherein the reflected ultrasonic energy is received by a sensing element at a center of the transducer. 
     
     
       5. The method of  claim 3 , further comprising calibrating individual transducer elements of the transducer based on the evaluated transducer performance. 
     
     
       6. The method of  claim 3 , wherein the transducer includes a plurality of transducer elements, and wherein the step of transmitting an emitted ultrasonic signal comprises simultaneously transmitting one or more ultrasonic signals from a set of the plurality of the transducer elements towards the acoustic reflector. 
     
     
       7. The method of  claim 6 , wherein the step of evaluating the transducer performance comprises: 
       obtaining a received ultrasonic characteristic from the received ultrasonic signal; and  
       comparing the received ultrasonic characteristic with a linear superposition of a like ultrasonic characteristic of the one or more emitted ultrasonic signals.  
     
     
       8. The method of  claim 6 , wherein the step of evaluating the transducer performance comprises determining a gain and phase shift of the received ultrasonic signal by comparing the amplitude and phase of the received ultrasonic signal with corresponding amplitudes and phases of the one or more emitted ultrasonic signals. 
     
     
       9. An ultrasound system, comprising: 
       a spherical cap transducer array including one or more transducer elements, the transducer elements configured for transmitting an emitted ultrasonic signal;  
       an acoustic reflector positioned to reflect at least a portion of an emitted ultrasonic signal transmitted by one or more of the transducer elements;  
       a sensing element located at a center of the spherical cap transducer array to receive a received ultrasonic signal comprising at least a portion of the ultrasonic signal reflected off of the acoustic reflector;  
       processing circuitry coupled to the sensing element for measuring an actual characteristic of the received ultrasonic signal; and  
       a controller coupled to the processing circuitry for comparing the actual characteristic of the received ultrasonic signal to an expected characteristic of the received ultrasonic signal;  
       wherein the acoustic reflector is positioned half-way between the spherical cap transducer array and its geometric focal point.  
     
     
       10. An ultrasound system, comprising: 
       a transducer including one or more transducer elements, the transducer elements configured for transmitting an emitted ultrasonic signal;  
       a planar acoustic reflector positioned to reflect at least a portion of an emitted ultrasonic signal transmitted by one or more of the transducer elements;  
       a sensing element positioned to receive a received ultrasonic signal comprising at least a portion of the ultrasonic signal reflected off of the acoustic reflector;  
       processing circuitry coupled to the sensing element for measuring an actual characteristic of the received ultrasonic signal; and  
       a controller coupled to the processing circuitry for comparing the actual characteristic of the received ultrasonic signal to an expected characteristic of the received ultrasonic signal,  
       wherein the transducer comprises a plurality of transducer elements and wherein the sensing element is positioned for receiving at least a portion of an ultrasonic signal reflected off of the acoustic reflector from each of the transducer elements.  
     
     
       11. The ultrasound system of  claim 10 , wherein the transducer comprises a spherical cap transducer array, and wherein the sensing element is located at a center of the spherical cap transducer array. 
     
     
       12. The ultrasound system of  claim 10 , wherein the processing circuitry is configured for measuring the actual characteristic of the received ultrasonic energy by comparing a characteristic of the received ultrasonic signal with a corresponding characteristic of the emitted ultrasonic signal. 
     
     
       13. The ultrasound system of  claim 12 , wherein the processing circuitry is further configured for comparing at least one of phase and amplitude of the received ultrasonic signal and the emitted ultrasonic signal. 
     
     
       14. A method for testing a focused ultrasound transducer, comprising: 
       transmitting an ultrasonic signal from a transducer element of a transducer array towards an acoustic reflector;  
       receiving the ultrasonic signal reflected off of the acoustic reflector from the transducer element at a sensing element that is different than the transducer element; and  
       evaluating performance of the transducer array based upon the ultrasonic signal received by the sensing element,  
       wherein the transducer array has a geometric focal point, and wherein the acoustic reflector comprises a planar reflector located between the transducer array and the geometric focal point.  
     
     
       15. The method of  claim 14 , wherein the transducer array comprises a plurality of transducer elements, and wherein the sensing element receives ultrasonic signals reflected off of the acoustic reflector from respective transducer elements. 
     
     
       16. The method of  claim 14 , wherein the performance is evaluated by comparing an actual characteristic of the ultrasonic signal received by the sensing element to an expected characteristic of the ultrasonic signal received by the sensing element. 
     
     
       17. The method of  claim 16 , wherein the actual characteristic comprises a difference between a component of an electrical signal generated by a sensing element that receives the ultrasonic signal, and a corresponding component of an electrical signal used to generate the ultrasonic signal. 
     
     
       18. The method of  claim 16 , wherein the actual characteristic is a gain comparing the amplitude of the ultrasonic signal received by the sensing element to the amplitude of the ultrasonic signal emitted by the transducer element. 
     
     
       19. The method of  claim 16 , wherein the actual characteristic is a delay between the ultrasonic signal received by the sensing element and the ultrasonic signal emitted by the transducer element. 
     
     
       20. The method of  claim 16 , wherein the ultrasonic signal emitted by the transducer element comprises a sinusoidal wave, and wherein the actual characteristic is a phase shift between the ultrasonic signal received by the sensing element and the ultrasonic signal emitted by the transducer element.